1. Field of the Invention
The present invention relates to a method of managing a queue of print jobs in a printer, wherein the jobs are created by specifying print data and print parameters for each job, and the jobs are put into the print queue, and wherein, before print processing of a job in the queue begins, a start condition for the job is checked and printing is started only when the start condition is fulfilled.
More specifically, the present invention is directed to a high production printer in which a plurality of jobs can be preprogrammed while the printer is busy with printing jobs that have been programmed earlier, so that, ideally, the jobs may be printed one after the other without interrupting the operation of the printer. The term “printer”, as used herein, refers to any kind of image reproducing machine that is capable of producing a hard copy of an image, and thus encompasses also copying machines, for example.
2. Discussion of Related Art
If the image to be printed can only be input through a unique data source, e.g. a scanning part of a copier, then, of course the data source does not have to be specified explicitly, and it will be understood that the unique data source is specified implicitly, for example by inputting a scan command in conjunction with the print parameters, e.g., the type and format of copying paper, the reproduction scale, the number of copies, and the like, that have been specified for this job.
If, for example, the print parameters that have been specified for a given job require that the copies are printed on paper with a format or quality that is presently not loaded in the machine, then a so-called start contradiction is encountered, which means that the start condition for this job has not been fulfilled and the job cannot be processed until the operator has loaded the required paper type into the machine. More generally, a start contradiction means that an intervention of the operator is necessary in order to fulfil the start condition for the job.
DE-A 41 07 000 describes a printer implementing a method in which a job, for which the start condition is not fulfilled, is automatically skipped, and the printer proceeds with processing the next job which follows in the queue and for which a start condition is fulfilled. In addition, a warning signal is output in order to alert the operator. This method has the advantage in that the presence of a job for which the start condition has not been fulfilled will not necessarily lead to an interruption of the production process. Instead, the machine will keep operating as long as jobs are present in the queue for which the start conditions are fulfilled. This will give the operator more time to intervene in order to fulfil the start conditions for the remaining jobs.
On the other hand, this method has the drawback in that the original sequence of the jobs in the queue is disturbed, so that the order in which the printed jobs are output from the machine differs from the order in which the jobs have been created by the operator. Since it can generally be assumed that the operator wants to receive the printed jobs in the same sequence in which the jobs have been input, this method leads to errors or inconvenience in the further processing and/or delivery of the printed jobs.
EP-A-0 469 865 discloses a printer in which the operator has the possibility to change the sequence of the jobs in the print queue either by sorting the jobs manually or by having them sorted automatically. In automatic sorting, one of the sort criteria may prescribe that the jobs for which the start conditions have been fulfilled in the present status of the machine are to be processed with higher priority than the jobs for which an intervention of the operator is necessary. However, if such a sorting routine is called-up, this will inevitably spoil the original sequence in which the jobs have been created.
EP-A-0 720 086 discloses a printer in which the criteria for deciding whether or not a start condition is fulfilled can be set by the user. Thus, the user may specify that, for example, a conflict between the color of copy paper prescribed in the print parameters and the colors of the copy papers presently loaded in the printer will not lead to a start contradiction. This would have the effect that the jobs will be printed in the original sequence, without interruption of the production process, but the copies would be printed on paper having the wrong color.